Peripheral arterial disease (PAD) affects 8 to 12 million individuals in the United States and is also prevalent in Europe and Asia (Allison et al., Am J Prev Med 2007; 32:328-33; Hasimu et al., Hypertens Res 2006; 29:23-8; Brevetti et al., J Cardiovasc Med (Hagerstown) 2006; 7:608-13; Hayoz et al., J Intern Med 2005; 258:238-43; Criqui et al., Circulation 2005; 112:2703-7). Classically, PAD causes limb fatigue or pain brought on by exertion and relieved by rest, i.e, intermittent claudication, and reduces functional capacity and quality of life (McDermott et al., Jama 2004; 292:453-61). It is frequently associated with coronary artery disease (CAD) and cerebral disease (McDermott et al., Jama 2004; 292:453-61; Steg et al., Jama 2007; 297:1197-206). Patients with PAD are at increased risk from myocardial infarction, stroke, aortic aneurysm, and vascular death, as well as ischemic ulceration and amputation (Steg et al., Jama 2007; 297:1197-206; Newman et al., Arterioscler Thromb Vasc Biol 1999; 19:538-45).
The high risk of vascular events in PAD is reduced by aggressive risk factor modification. In these individuals, the use of statins, angiotensin converting enzyme inhibitors, and antiplatelet therapy reduces morbidity and mortality (Hankey et al., Jama 2006; 295:547-53). Unfortunately, PAD is underdiagnosed and undertreated. In fact, many of those affected do not manifest the classic symptomatology. Classic claudication is only noted by 10-30% of patients (McDermott et al., Jama 2004; 292:453-61; Hirsch et al., Jama 2001; 286:1317-24) and atypical leg discomfort occurs in 20-40% (McDermott et al., Jama 2001; 286:1599-606). Up to 50% of patients do not complain of leg symptoms. However, even these individuals have a reduced lifespan without aggressive treatment (McDermott et al., Jama 2004; 292:453-61; Criqui et al., N Engl J Med 1992; 326:381-6; Vogt et al., Jama 1993; 270:465-9; Newman et al., J Am Geriatr Soc 1997; 45:1472-8). In other situations, individuals may be suffering from other circulatory maladies (e.g., coronary artery disease) whose symptoms may obscure a diagnosis of PAD.